Anyone who saw Bruce Springsteen at the Capital Centre Thursday night and still has some time and money left can use this week to trace the development of one aspect of rock'n'roll over the last 15 years or so. Having Springsteen, Bob Seger and Van Morrison in town within a week demonstrates the popularity of the intense, direct rock sound they all represent, and Monday night's Van Morrison concert highlights a crammed week of music.

Seger brings his Silver Bullet Band to the Capital Centre Friday night and Morrison follows him here with a new band, a new album, a new manager and an old reputation for presenting a great show.

Though Morrison's appearance at Constitution Hall is scaled smaller than the other two, his may well be the most important. Both Springsteen and Seger have finally established themselves as major forces in contemporary music, but Morrison has already been there and back. Springsteen is considered by many to be rock's new standard-bearer, with Seger benefiting from that type of music's new-found acceptance, but Morrison is the key. He's the seminal influence who affected them both.

If one were to draw a musical genealogy chart, Morrison would head this week's concert list. Springsteen adapted some of Van's stronger characteristics to his own style, while Seger blended the best of both with his distinctive delivery.

Morrison has Springsteen's vitality and pace, but lacks his animal grace. He has Seger's earthy sincenity, but not the rock-solid backbeat that fuels most of Seger's best times. Morrison, despite his tenure, is less polished. Yet it's the resulting unpredictability that makes him so interesting.

Van Morrison came out of Ireland in 1964 as lead singer for Them and made a name for himself with "Here Comes the Night" and "Gloria," which Springsteen performed during his August concert at the Capital Centre. A year later, he left them and scored as a solo act with "Brown Eyed Girl." Between 1968 and 1971, Morrison built an impressive catalog of songs.

The album "Astral Weeks," a critical classic but a commercial failure, used bona fide jazz players including Jay Berliner, Connie Kay, Richard Davis and John Payne in the supporting band.

"Moodance," the hit that established Morrison with the masses, also contained "Come Running," "Into the Mystic" and "Caravan"; he trumped those with songs' like "Domino" and "Wild Night."

Things eased up after the "Tupelo Honey" album - neither "St. Dominic's Preview" nor "Hard Nose the Highway" came up to expectations, either artistically or commercially.But "It's Too Late to Stop Now" was a heart-stopping two-record live set in which Morrison proved that he was still one of the highest-quality performers on the scene.

What happened next is something that all artists fear a sudden lack of ideas. "Veedon Fleece," released in 1974, did nothing to enhance Morrison's fading compositional strengths, and he couldn't come up with a successor until last year, with "Period of Transition," which was an obvious effort - his audience to hear.

Now we have "Wavelength," and it's miles above "Period of Transition," though not quite up to the Morrison of the early '70s.

The primary difference between this year's Morrison and last year's is the same as between this year's Morrison and that of 1970: the quality of his material.

"Wavelength" flexes some of the old muscle in the title cut and "Natalia," both crafted for the mainstream but stylized into more complex pieces; "Kingdom Hall" rocks nicely, while "Checkin' It Out" is loose and breezy. Yet there's a tentativeness to the album, a feeling that if you dig too deeply, it will all come apart. "Lifetimes" sounds like a lot of other Morrison songs, especially "Caravan." "Santa Fe / Beautiful Obsession" might have been a classic but trips over itself just when it's about to catch fire. "Take It Where You Find It" would probably have been stronger at half its length.

The most blatant example of Morrison's tendency toward writer's block is "Hungry for Your love." One look at the lyric sheet tells you why it sounds like Morrison isn't saying anything. He isn't.

Still, what sets this album apart from pack is the way Morrison's intensity pervades his work. You can hear him experimenting, shading phrases and using blue notes for melodic variation. Even though his words sometimes drift into patterns, Morrison himself is so sincere that he books you despite the weaknesses.

"Wavelength" suggests that Morrison is regaining his somewhat tarnished luster. His affiliation with Bill Graham has given him visibility, and his current tour will go a long way toward recharging his energy. In "The Last Waltz," Morrison displayed his ability to mesmerize an audience on sheer personality. That might be enough for many acts, but with Morrison the music is most important.

His latest music has a street toughness that's fashionable again, and all his work is complemented by an underlying warmth. He has a jazz sensibility with a rock foundation, and he tinges his blues with a brogue. The bottom line is that Van Morrison is good enough to have influenced stars now bright enough to be influences themselves.

"Wavelength" is the appetizer for a full-course concert by an artist who could retire tomorrow with his place in pop music solidly established. He's gambling by going forward at his own speed instead of the public's, but he has never played it safe. And rock'n'roll is a bit better for that.